This document provides a framework for understanding and applying usability to interactive systems, and to other types of systems (including built environments), products, and services. NOTE In this document the phrase system, product or service refers to the identified object of interest for usability (see 8.1). This part of ISO 9241: explains the concept of usability as an outcome of interaction; provides definitions; identifies the fundamentals of usability; and describes the application of the concept of usability. This document does not provide guidance or describe specific processes and methods for the application and evaluation of usability. The concept of usability as described in this document can be used in situations where people use a system (including interactive systems and built environments), products (including industrial and consumer products), or services (including technical and personal services). The intended users of this document include: usability/ergonomics/human factors professionals; developers of systems, products and services; quality assurance personnel; public and corporate purchasers; consumer organizations. The most common applications of this document are in design and evaluation.